Pump driving unit for driving a pump used for supporting or substitution of cardiac function

ABSTRACT

In a small sized pump driving unit, a fluid pump is used for driving the pump for supporting of substituting of cardiac function. The fluid pump can generates pressure fluctuations that can generate pulsation of the pump for supporting or substituting of cardiac function and produces sufficient performance to drive the pump unit.

[0001] The entire disclosure of Japanese Patent Applications No.2000-129596 filed on Apr. 28, 2000 and No. 2001-074968 filed on Mar. 15,2001, including the specification, drawings and abstract, isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention generally relates to a pump driving unitfor driving a pump used for supporting or substituting of cardiacfunction, such as a blood pump which is applied to an artificial heartor a intra-aortic balloon pump which supports cardiac function. Moreparticularly, this invention provides for miniaturization of the pumpdriving unit.

[0004] 2. Description of the Background

[0005] A known type of a pump driving unit for driving a pump used forsupporting or substitution of cardiac function, such as a blood pump orIABP (Intra-Aortic Balloon Pump) is disclosed in Japanese PatentLaid-Open Publication No. 11-188091. This publication discloses an airpressure driven type pump driving unit, which drives a pump used for anartificial heart.

[0006] A conventional air pressure driven type pump driving unit such asthe above cited publication, generally has a compressor, a high pressureaccumulation chamber and a low pressure accumulation chamber, and isplaced outside of a human body. The high pressure accumulation chamberis connected to an output port of the compressor and the low pressureaccumulation chamber is connected to an intake port of the compressor,respectively. These two accumulation chambers are connected to aconnection port of the artificial heart through a selector valve. Inresponse to an operation of the selector valve, these accumulationchambers are selectably communicated with the connection port, andpressure fluctuation thereby occurs. The pressure fluctuation which isgenerated between these pressure accumulation chambers drives a pumpused for supporting or substitution of cardiac function.

[0007] The conventional air pressure driven type pump driving unit musthave a compressor, and high and low pressure accumulation chambers, andso is bulky. To reduce the size of the driving unit, U.S. Pat. No.5,766,207 suggests placing the compressor in the low pressureaccumulation chamber. However, the unit still requires a compressor anda low pressure accumulation chamber, which limits the size reduction ofthe pump driving unit. Since the pump driving unit must always accompanythe user, this limits the user's range of activity.

SUMMARY OF THE INVENTION

[0008] In view of above mentioned disadvantage of the conventionaldriving unit, it is an object of the present invention to produce a pumpdriving unit that has minimized unit size.

[0009] To achieve the above and other objects, a pump driving unit fordriving a pump used for supporting or substitution of cardiac functioncomprises a fluid pump which is a driving source of the pump used forsupporting or substitution of cardiac function.

[0010] Further, the pump driving unit for driving a pump used forsupporting or substituting of cardiac function comprises an isolatorforming therein a first space, and a second space divided from the firstspace by a flexible member and connected to the pump, a fluid pumpconnected to the first space and operated so as to supply a fluid mediatherein to the first space or to suck a fluid media into the firstspace, and a control unit for controlling an operation of the fluidpump.

[0011] The fluid pump generates sufficient pressure fluctuations togenerate pulsative operation of the pump used for supporting orsubstitution of cardiac function such as the blood pump or the balloonpump, and need not use an accumulation chamber to adjust the pressure.Therefore, the pump driving unit can have a small size. Further, thefluid pump is smaller than a compressor so that the size of the pumpdriving unit can be minimized.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Additional features and characteristics of the present inventionwill become more apparent from the following detailed descriptionconsidered with reference to the accompanying drawing figures in whichlike elements are designed by like reference numerals and wherein:

[0013]FIG. 1 illustrates a structure of the first embodiment of a pumpdriving unit according to the invention; and

[0014]FIG. 2 illustrates a structure of the second embodiment of a pumpdriving unit according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0015] This invention will be described in according to preferredembodiments which are shown in attached drawings.

[0016] (First Embodiment)

[0017]FIG. 1 shows a schematic structure of the first embodiment of theinvention. A pump driving unit 1 has an isolator 11, a fluid pump 12, acontrol unit 13 and a reservoir tank 14. The aforementioned elements areretained in a housing 100.

[0018] The interior of the isolator 11 is divided into a first space 112and a second space 113 by a flexible member such as a diaphragm 111. Inthis embodiment, the diaphragm 111 is made from fluorine rubbermaterial.

[0019] The fluid pump 12 pulsatively drives a blood pump 51. In otherwords, the fluid pump 12 is used as a driving source of the blood pump51. A turbine type fluid pump 12 is used in this embodiment. An impellerturbine 122 is disposed in a pump housing 121. The fluid pump 12 rotatesin both clockwise and counterclockwise directions. The pump housing hasa first port 121 a and a second port 121 b. The first port 121 acommunicates with the first space 112 of the isolator 11 through a fluidpath 21. The second port 121 b communicates with the reservoir tank 14through a fluid path 22. The impeller turbine 122 is driven by a motor123. The motor 123 drives the impeller turbine 122 bidirectionally, thatis, in either a clockwise direction (shown by arrow B in FIG. 1) or acounterclockwise direction (shown by arrow A in FIG. 1). A rotationalspeed of the motor 123 is variably controlled through the control unit13. A brushless motor or a stepping motor can be used as the motor 123in this embodiment.

[0020] A first pressure sensor 31 is arranged at the first space 112 anda second pressure sensor 32 is arranged at the second space 113 todetect actual pressure levels in these spaces. The detected actualpressure levels in the isolator are transmitted to the control unit 13.

[0021] The second space 113 communicates with the blood pump 51 througha fluid path 23. An intake and exhaust control valve 41 is mounted inthe path 23 to control a pressure level in the path 23. A two way(open-close) valve is used in this embodiment, and the valve 41 iscontrolled by the control unit to retain the pressure level in the path23 within a predetermined range.

[0022] The control unit 13 controls the operation of the fluid pump 12through the motor 123 and the operation of the intake and exhaustcontrol valve 41. In order to coordinate appropriate user conditions,the control unit 13 controls motor 123 and the intake and exhaustcontrol valve 41 by using signals from first and second space pressuresensor 31 and 32. The motor 123 is controlled in its direction andspeed, and the intake and exhaust control valve 41 is controlled in itsopen-close ratio.

[0023] The blood pump 51 has a housing 511 and a diaphragm 512. Theinner space of the blood pump 51 is divided into a fluid chamber 513 anda blood chamber 514 by a diaphragm 512. The second space 113 of theisolator 11 is communicated with the fluid chamber 513 of the blood pump51.

[0024] A liquid such as silicon oil is liquid tightly held in the firstspace 112, the path 21, the fluid pump 12 , the path 22 and thereservoir tank 14. A gas such as air is gas tightly held in the secondspace 113, the path 23 and the fluid chamber 513 of the blood pump 51.Therefore, an upstream side (first side fluid) of the diaphragm 111 iscontacted by silicon oil as a fluid media and a downstream (second sidefluid) of the diaphragm 111 is contacted by air.

[0025] The operation of the first embodiment is described hereinafter.When the fluid pump 12 is driven in a counterclockwise (positive)direction (arrow A direction in FIG. 1), silicon oil in the fluid pump12 is sent to reservoir tank 14 through the path 22 and silicon oil inthe first space 112 is sucked by the fluid pump 12 through the path 21and the first port 121 a. In response to this operation, the pressurelevel in the first space 112 is decreased and the diaphragm 111 moves inthe left direction (shown by arrow D) in FIG. 1. Consequently, thevolume of the first space 112 is decreased and the volume of the secondspace 113 is expanded. According to the expansion of the volume of thesecond space 113, the pressure level in second space 113 will bereduced. This decompression is transmitted to the fluid chamber 513 ofthe blood pump 51 through the path 23 so that the volume of the fluidchamber 513 is decreased and the shape of the diaphragm 512 istransformed from the illustrated concave shape to a convex shape. As aresult of this transformation of the shape of the diaphragm 512, theblood chamber 514 is pulsatively driven and blood is taken in.

[0026] When the fluid pump 12 is driven in a clockwise direction(negative direction) which means arrow B in FIG. 1, silicon oil in thereservoir tank 14 is sent to the fluid pump 12 through the path 22 andthe second port 121 b, and silicon oil in the fluid pump 12 is sent tothe first space 112 through the first port 112 a and the path 21. Inresponse to this operation, the pressure level in the first space 112 isincreased and the diaphragm 111 moves in the right direction (shown inarrow C) in FIG. 1. Consequently, the volume of the first space 112 isexpanded and the volume of the second space 113 is decreased. Accordingto the decreasing volume of the second space 113, the gas in the secondspace 113 will be compressed. This compression is transmitted to thefluid chamber 513 of the blood pump 51 through the path 23 so that thevolume of the fluid chamber 513 is increased and the diaphragm 512 istransformed from a convex shape to a concave shape. In terms of thistransformation of the diaphragm 512, the blood chamber 514 ispulsatively driven and blood is output from the fluid pump 51.

[0027] Due to this counterclockwise and clockwise rotation of the fluidpump, the blood pump 51 is pulsatively driven. The rate of fluid pumpoperation (cycle of between counterclockwise and clockwise operation)determines the pulse of the blood pump 51.

[0028] The transformation of the diaphragm 512, which includes the pulseoperation of the blood pump 51, depends on the pressure level of thesecond space 113 and the fluid chamber 513. In this embodiment, thepressure levels in the second space 113 and the fluid chamber 513 is setto be within the range from −26.6 Kpa to +39.9 Kpa (equal to −200 mmHgto +300 mmHg). Pressure adjustment within the above described range andthe rising or falling of the pressure level are controlled by therotation speed of the fluid pump 12. The rotation speed of the fluidpump 12 is adjusted by controlling the output and/or intake amount ofsilicon oil. However, in the conventional pump driving unit, thispressure adjustment is performed by using a high pressure accumulationchamber and a low pressure accumulation chamber. In the presentinvention, the blood pressure in the blood pump 51 is appropriatelyadjust by controlling the rotational speed of the fluid pump 12, whicheliminates the need for high and low pressure accumulation chambers.

[0029] (Second embodiment)

[0030]FIG. 2 shows a schematic structure of the second embodiment of theinvention. In this second embodiment, a balloon pump driving unit 2drives the balloon pump 61 instead of the blood pump 51. The samefeatures as in the first embodiment are given the same numbers.

[0031] The balloon pump 61 is connected to the isolator 11 through thefluid path 23. The balloon pump 61 is installed in a patient's mainartery (e.g., downstream main artery) and repeatedly shrinks and expandsin response to the movement of the heart. The balloon pump 61 minimizesthe burden of the heart and supports cardiac function.

[0032] A gas such as helium gas fills the second space 113, the path 23and the balloon pump 61. Since helium gas is an inert gas, the gas issafe. Also, since it has low inertia, it enables high responsiveness forthe balloon pump drive unit 2.

[0033] A helium gas storage cylinder 42 (means for helium gas supply tothe balloon pump) is installed in the path 23 via an intake and exhaustcontrol valve 41. When the amount of helium gas in the path 23 and/orthe balloon pump 61 decreases, the helium gas storage cylinder 42supplies additional helium gas.

[0034] As shown in FIG. 2, a pressure maintaining valve 43 is installedon the path 23 and is placed downstream of the intake and exhaustcontrol valve 41. The pressure maintaining valve 43 controls thepressure in the balloon pump 63 by, and is controlled in its opening andclosing by the control unit 13.

[0035] When the fluid pump 12 is driven in the counterclockwisedirection (positive direction), which means arrow A in FIG. 2, siliconoil in the fluid pump 12 is sent to the reservoir tank 14 through thesecond port 121 b and the path 22, and silicon oil in the first space112 is sucked by the fluid pump 12 through the path 21 and the firstport 121 a. In response to this operation, the pressure level in thefirst space 112 is reduced and the diaphragm 111 moves in the leftdirection (shown by arrow D) in FIG. 2. Consequently, the volume of thefirst space 112 is decreased and the volume of the second space 113 isexpanded. According to the expansion of the volume of the second space113, the gas in the second space 113 will be decompressed. Thisdecompression is transmitted to the balloon pump 61 through the path 23,and the volume of the balloon pump 61 is decreased and the balloon pump61 shrinks.

[0036] When the fluid pump 12 is driven in the clockwise direction(negative direction), which means arrow B in FIG. 2, silicon oil in thereservoir tank 14 is sent to the fluid pump 12 through the path 22 andthe second port 121 b, and silicon oil in the fluid pump 12 is sent tothe first space 112 through the first port 121 a and the path 21. Inresponse to this operation, the pressure level in the first space 112 isincreased and the diaphragm 111 moves in the right direction (shown inarrow C) in FIG. 2. Consequently, the volume of the first space 112 isexpanded and the volume of the second space 113 is decreased. Accordingto the decreasing of the volume of the second space 113, the gas in thesecond space 113 will be compressed. This compression is transmitted tothe balloon pump 61 through the path 23 and the volume of the balloonpump 61 is increased and the balloon pump 61 expands.

[0037] According to the counterclockwise and clockwise rotation of thefluid pump operation, the balloon pump 61 repeatedly expands and shrinksso that the balloon pump 61 supports blood flow and minimizes the burdenof the heart and supports cardiac function.

[0038] In this embodiment, the pressure level in the balloon pump 61 isset within the range from −13.3 Kpa to +26.6 Kpa (equal to −100 mmHg to+200 mmHg). The pressure adjustment within the above described range andthe rising or falling of the pressure level are controlled by rotationspeed of the fluid pump 12. The rotation speed of the fluid pump 12 isadjusted by controlling the output and/or intake amount of silicon oil.In the conventional driving unit, this pressure adjustment is performedby using a high pressure accumulation chamber and a low pressureaccumulation chamber. In the present invention, the blood pressure inthe blood pump 51 is appropriately adjusted by controlling therotational speed of the fluid pump 12, and so the high and low pressureaccumulation chambers are unnecessary.

[0039] In this second embodiment, the pressure maintaining valve 43,which is controlled by the control unit 13, controls rapid pressureincreasing and rapid pressure decreasing in the balloon pump fit.

[0040] The rapid pressure increasing is accomplished in accordance withfollowing operation. When the balloon pump 61 is at a low pressurecondition, the pressure maintaining valve 43 is closed by the controlunit 13. The balloon pump 61 and the second space 113 of the isolator 11are thus cut off from each other. Under this condition, the motor 123drives the impeller turbine 122 in a clockwise direction (negativedirection and shown an arrow B in FIG. 2) and silicon oil in the fluidpump 12 is supplied to the first space 112 of the isolator 11 so thatthe gas pressure level in the second space 113 is increased. Thepressure level in the balloon pump 61 remains low because the pressuremaintaining valve 43 is closed. When the pressure level in the secondspace 113 reaches a sufficiently high pressure level, the pressuremaintaining valve 43 is opened by the control unit 13. In response tothis operation, the accumulated pressure in the second space 113 isintroduced into the balloon pump 61 in a burst and the pressure level inthe balloon pump 61 rapidly changes from low pressure to high pressure.

[0041] A rapid pressure decrease is accomplished in accordance withfollowing operation. When the balloon pump 61 is in a high pressurecondition, the pressure maintaining valve 43 is closed by the controlunit 13. The balloon pump 61 and the second space 113 of the isolator 11are thus cut off each other. Under this condition, the motor 123 drivesthe impeller turbine 122 in counterclockwise direction (positivedirection and shown by an arrow A in FIG. 2), and the silicon oil in thesecond space 113 is sucked by the fluid pump 12 through the path 21 andthe first port 121 a, and the pressure level in the second space will bereduced. The pressure level in the balloon pump 61 remains high becausethe pressure maintaining valve 43 is closed. When the pressure level inthe second space 113 reaches a sufficiently low pressure level, thepressure maintaining valve 43 is opened by the control unit 13. Inresponse to this operation, the pressure in the balloon pump 61 isintroduced into the second space 113 in a burst and then the pressurelevel in the balloon pump 61 rapidly changes from high pressure to lowpressure.

[0042] According to this rapid pressure operation, the balloon pump hashigh responsiveness.

[0043] In this present invention, the fluid pump 12 generates sufficientpressure fluctuations to generate pulsative operation of the pump usedfor supporting or substitution of cardiac function such as the bloodpump or the balloon pump, and need not use an accumulation chamber toadjust the pressure. Therefore, the size of the pump driving unit can beminimized. Further, the fluid pump is smaller than a compressor, so thatthe pump driving unit can be miniaturized.

[0044] Further, in the present invention, the driving unit for drivingthe pump used for supporting or substitution of cardiac function has theisolator 11 that has divided first and second spaces 112 and 113, thefluid pump 12 that supplies silicon oil to the first space or suckssilicon oil from the first space 112, and the control unit 13 thatoperates the fluid pump 12. In response to supply and sucking operationsof the fluid pump 12, pulsative operations are generated in the pump.Therefore, it is not necessary to use an accumulation chamber, and thedriving unit size can be reduced.

[0045] Furthermore in the present invention, since the pump driving unithas a fluid pump that can be driven in either a positive or negativedirection, no control valve is required to control fluid supply andsucking from the pump driving unit. Therefore, the pump driving unit canbe manufactured at a lower cost.

[0046] According to the first embodiment, the pump driving unit uses theblood pump 51 as the pump used for supporting or substitution of cardiacfunction. According to the second embodiment, the pump driving unit usesthe balloon pump 61 as the pump used for supporting or substitution ofcardiac function. The present invention therefore enables a smaller pumpdriving unit.

What we claim is:
 1. A pump driving unit for driving a pump used forsupporting or substitution of cardiac function, comprising a fluid pumpwhich is driving source of the pump used for supporting or substitutionof cardiac function.
 2. A pump driving unit for driving a pump used forsupporting or substituting of cardiac function as set forth in claim 1,wherein the pump used for supporting or substituting of cardiac functionis a blood pump.
 3. A pump driving unit for driving a pump used forsupporting or substituting of cardiac function as se forth in claim 1,wherein the pump used for supporting or substituting of cardiac functionis a balloon pump.
 4. A pump driving unit for driving a pump used farsupporting or substituting of cardiac function as set forth in claim 1,wherein the fluid pump comprises an impeller turbine which is able torotate in two directions.
 5. A pump driving unit for driving a pump usedfor supporting or substituting of cardiac function comprising: anisolator forming therein a first space, and a second space divided fromthe first space by a flexible member, said second space connected to thepump used for supporting or substituting of cardiac function, wherein afluid pump is connected to the first space so as to supply a fluid mediatherein to the first space or to suck a fluid media in the first space;and a control unit adapted for controlling an operation of the fluidpump.
 6. A pump driving unit far driving a pump used for supporting orsubstituting of cardiac function as set forth in claim 5, wherein thepump used for supporting or substituting of cardiac function is a bloodpump.
 7. A pump driving unit for driving a pump used for supporting orsubstituting of cardiac function as set forth in claim 5, wherein thepump used for supporting or substituting of cardiac function is aballoon pump.
 8. A pump driving unit for driving a pump used forsupporting or substituting of cardiac function as set forth in claim 7,further comprising a pressure maintaining valve disposed between thesecond space and the pump used for supporting or substituting of cardiacfunction.
 9. A driving unit for driving a pump used for supporting orsubstituting of cardiac function as set forth in claim 7, wherein heliumgas is filled in a volume between the second space and the pump used forsupporting or substituting of cardiac function.
 10. A pump driving unitfor driving a pump used for supporting or substituting of cardiacfunction as set forth in claim 9, further comprising means for heliumgas supply to the balloon pump, the means for helium gas supply beingconnected between the second space and the balloon pump via an intakeand exhaust valve.
 11. A pump driving unit for driving a pump used forsupporting or substituting of cardiac function as set forth in claim 5,wherein the fluid pump comprises an impeller turbine which is able torotate in two directions, and a fluid is supplied to the first spacewhen the impeller turbine is driven in a negative direction.
 12. A pumpdriving unit for driving a pump used for supporting or substituting ofcardiac function as set forth in claim 5, wherein the fluid pumpcomprises an impeller turbine which is able to rotate in two directions,and a fluid in the first space is sucked into the fluid pump when theimpeller turbine is driven in a positive direction.
 13. A pump drivingunit for driving a pump used for supporting or substituting of cardiacfunction as set forth in claim 5, further comprising a first pressuresensor arranged at the first space, and a second pressure sensorarranged at the second space.
 14. A pump driving unit for driving a pumpused for supporting or substitution of cardiac function, comprising: abidirectional fluid pump; and means for operating the pump used forsupporting or substitution of cardiac function based on a speed anddirection of operation of said fluid pump.
 15. A pump driving unit fordriving a pump used for supporting or substitution of cardiac function,comprising: a bidirectional fluid pump driven by a motor; a fluidisolator having two spaces separated by a diaphragm, one of said spacesreceiving a fluid pressure from said fluid pump, the other of saidspaces being fluidically connected to the pump used for supporting orsubstitution of cardiac function; and a controller which controls aspeed and direction of operation of the motor driving said fluid pumpbased on a fluid pressure in at least one of said spaces.
 16. A pumpdriving unit for driving a pump used for supporting or substituting ofcardiac function as set forth in claim 15, further comprising a firstpressure sensor arranged at the first space, and a second pressuresensor arranged at the second space.
 17. In a pump driving unit fordriving a pump used for supporting or substitution of cardiac function,the pump driving unit comprising a bidirectional fluid pump driven by amotor, and a fluid isolator having two spaces separated by a diaphragm,one of said spaces receiving a fluid pressure from said fluid pump, theother of said spaces being fluidically connected to the pump used forsupporting or substitution of cardiac function, a method for driving thepump used for supporting or substitution of cardiac function, the methodcomprising the steps of: determining a fluid pressure in at least one ofsaid spaces; and controlling a speed and direction of operation of themotor driving said fluid pump based on the determined fluid pressure.